This work has a very extensive inscription encircling the bottom of the base, which translates as follows:
By the assistance of the best virtue, and with the help of
the understanding of the complete meanings of buddha’s teachings,
Leg pei jun nas who practice to understand the insight meaning of Mahayana,
I pray to and prostrate to his feet and blessed all the times.
A second inscription is visible at the front edge of the top of the base, just past the lama’s robes, which gives his name (glo bo mkhan chen bsod nams lhun grub).
Lowo Khenchen Sonam Lhundrub (glo bo mkhan chen bsod nams lhun grub, 1456-1532) was born into the ruling house of Lo Montang (glo mon thang, also known as Mustang). He was dedicated to the religious life from infancy, receiving transmissions and teachings of empowerment from famous teachers throughout his childhood. He eventually became the abbot at Tubten Dargyeling for twelve years, and then moved to Ngor Monastery in Tibet. He ultimately returned to Lo, where he continued to propagate the Ngor tradition of the Sakya teachings through writing and ritual instruction there and in neighboring kingdoms. For his complete bibliography, see Himalayan Art Resources (himalayanart.org).
Compare this figure with a similar example from The Sporer Collection (illustrated below). Both have silver- and copper-inlaid eyes and copper lips, and hold lotuses bearing the book and sword, connecting their lineage to Manjushri. The present example is larger than the Sporer example, with a much more extensive inscription. The quality of the casting, the inclusion of inlaid silver and copper, and the substantial size, indicates Sonam Lhundrub was an important teacher worthy of such a fine portrait.